Why does Lenz's law have a minus sign?
The minus sign shows that the direction of induced current always opposes the change that created it. So when certain metals are cropped through say a copper tube they slow down. Show video of Lenz's law in action. The current is induced in the opposite direction to ensure that energy is conserved and not created from nothing.
When pushing a magnet into a coil, if you push the North pole towards the coil first then a North pole is induced in the coil to repel the magnet. The magnet is slowed down and repelled by the coil, the kinetic energy here is dissipated as heat.
JJ
Related Physics A Level answers
All answers ▸Two electrons are a distance r apart, the first electron exerts a force F on the second electron. a) What force does the second electron exert on the first? b) In terms of r, at what distance is the force that the first electron exerts on the second F/9?
Please explain how polarisation of waves occurs?
a solar cell of area 2m^2 has maximum a power output per unit area of 20W/m^2 . if four solar cells are used together at once, how much energy is release in 2 mins at max power output?
Calculate the kinetic energy of a car of mass 1.0*10^3kg moving at speed of 20ms^-1.